1. Field of the Invention:
The present invention is directed to a method for identifying a power output by a laser onto a workpiece, and more particularly to identifying the power output by a laser onto a workpiece in laser welding based on the dependency of sound emission signals which occur in the workpiece.
2. Description of the Prior Art
Previous methods for estimating the laser power output onto a workpiece either use a temperature measurement in the workpiece for this purpose, or measure the laser light power not absorbed by the workpiece, this then being subtracted from the set laser power. As can be seen from the German Pat. No. 30 29 957, corresponding to the European application No. 0 045 942, the sound emission signal occurring during a cutting process is evaluated for judging the wear at cutting tools. Sound emission analysis is based on the phenomenon that glide processes or, respectively, phase conversions occurring during the deformation of a metal emit sound pulses whose frequencies extend far into the ultrasound region. In general, the sound emission analysis is utilized as a method for non-destructive metals testing. A precise description thereof is supplied in the article "Schallemissionsanalyse", published in the Ingenieur Digest, Vol. 11, No. 10, 1972, pp. 62 et sec.